Ultrasonic cleaning equipment



May 2, 1961 M. R. BLAND uLTRAsoNIc CLEANING EQUIPMENT 5 Sheets-Sheet 1Filed Sept. 15, 1958 IIIIIIIIIIIIIII l' JNVENToR. Mes/4MM JQ. 5MM/0Arrow/EVS.

May 2, 1961 M. R. BLAND 2,982,524

ULTRASONIC CLEANING EQUIPMENT Filed Sept. l5, 1958 5 Sheets-Sheet 2rraeA/ys May 2, 1961 M. R. BLAND ULTRAsoNIc CLEANING EQUIPMENT Filedsept. 15, 1958 3 Sheets-Sheet 5 i Unit thee Patented May 2, 1961ULTRASONIC CLEANING EQUIPMEN Marshall R. Bland, La Habra, Calif.,assigner, by rnesne assignments, to Purex Corporation, a corporation ofCalifornia Filed Sept. 15, 1958, Ser. No. 760,987

17 Claims. (Cl.259-1) the high velocity rotation of specific shapedgenerators including a Wedge type sound generator by a .propeller in abody of liuid being displaced at high velocity toward and from acleaning zone by the propeller so as to produce ultrasonic wave energyin the cleaning zone acting in cooperation with the liquid to removesoils from the parts.

Speaking generally with respect to the prior artV concerning ultrasoniccleaning, the applicators or transducers previously used for suchcleaning and of which I am aware have been mounted so as to benon-movable during their operation to produce ultrasonic wave energypropagated into the coupling solution within which the parts to becleaned are immersed for producing cavitation at the parts surfaces.Electro-mechanical transducers typically used for this purpose arenecessarily rather complex and therefore are conned to a fixed positionrelative to the receptacle containing the cleaning liquid. However, suchfixed positioning of transducersdoes not best promote the distributionof liquid cavitation over extended surfaces of parts to be cleaned, theparts normally 'being stacked in different random positions in a basketlowered into a cleaning zone within a liquid receptacle. `As aresuit,.certain surfaces ofthe parts closer to the transducer will receiveymore ultrasonic treatment than `other parts surfaces located remotelyor at a greater distance from the transducer, and such differentialtreatment makes the degree and time of cleaning unpredictable. I `amaware that attempts have been made to overcome this problem through theuse of many xed location.electro-mechanical transducers; however, suchprovision is extremely expensive and hence `prohibitive in low costcleaning equipment.

The present invention seeks to avoid the difficulties mentioned abovethrough the provision of a fluid dynamic wedgevtype sound generatorbodily rotated in a moving body of cleaning liquid at a speed suflicientfor the production of ultrasonic energy. Such rotation serves not onlyto effect production `of the desired ultrasonic Wave energy, but also tomove the energy source in relation to the parts surfaces to be cleanedso that no parts surfaces remain located at fixed distances from thegenerator. As a result, more nearly uniform cleaning rates for all partssurfaces -are realized, with consequent decreased differential cleaningtreatment of differently located parts surfaces. rotary means carryingit is simplevto manufacture, does not have orifices subject to clogging,and is capable of producing utrasonics at relatively low velocities in aliquid bath. Operation of the 'generator is characterized byrelativeflowage of liquid pastanedge or edges of the wedge In addition,the wedge-type generator and the l being rotated through liquid at suchhigh velocity and reduced pressure that ultrasonic waves are producedand propagate into the tank cleaning zone. Also, a broad spectrum ofultrasonic frequencies is produced for efficient cleaning treatment ofmany different objects coated with different soils, as distinguishedfrom the rather narrowl spectrum of ultrasonic frequencies produced byelectromechanical transducers.

Accordingly, it is a major object of the present invention to provideultrasonic cleaning equipment broadly comprising rotary means axiallyrotatable in a body of liquid and wedge means carried by the rotarymeans for high velocity rotary displacement in the liquid in thedirection of wedge taper relatively to accelerate liquid over y' the`wedge tapering surface or surfaces and producing u1- trasonicdisturbances propagating in the liquid and acting to aid cleaning ofparts inserted therein. More speciically, the invention contemplatesrotation of the wedge means by an axial fiow propeller received Within arecess in the side wall of a cleaning receptacle and opposite a cleaningzone in the receptacle, so that ultrasonic disturbances propagate inliquid being displaced laterally into the cleaning Zone by the propellerto aid cleaning of parts in that zone, the recess walls acting to` guidethel liquid flo-w in most eflicient relation to the .propeller and partscleaning zone and also to reflect ultrasonic wave energy toward theinterior of the cleaning zone.

The wedge means referred to will typically include relatively forwardlytapering opposite sides at least one of which has forwardly andrearwardly spaced sharply defined edges over whichthe liquid relativelyaccelerates by a Bernoulli effect, causing the relative'ow velocity toincrease and the pressure to sharply decrease at one and preferablyopposite sides of the Wedge, and resulting in the formation at the sharpedges of the wedge of cavitation bubbles in the liquid. The formationand collapsing of these bubbles will in general produce vperiodicpressure changes propagating in the liquid :as waves of ultrasonicfrequency. v

The invention furthermore Acontemplates mounting one or more Wedgeseither on a ring coaxial with and carried by a screw propeller or on thepropeller blades themselves, the wedges being arranged both circularlyand radially with respect to the propeller axis, and the wedges taperingin opposite directions of propeller rotation to facilitate sonic energyproduction during y'both forward and reversecycling of the propeller, asywilll be described.

These and other objects and advantages of the invention. as well as thedetails of an illustrative embodiment, will be more fully understoodfrom the following detailed description of the drawings, in which:

Fig. 1 is a side view of one form of the complete cleaning apparatusshowing the receptacle partly broken away to show the interiorconstruction thereof and the flow of liquid therein;

Fig. 2 is an end elevation of the exterior of the receptacle;

Fig. 3 is a view taken on `line 3-3 of Fig. l;

Fig. 4 is an enlarged frontal view of the propeller shown in yFigsl 1and 3 and showing the sonic generators carried byV the propeller; i l lFig. 5 is a view simzlar to Fig. 4 showing the manner in which the sonicgenerators may be mounted to the propeller blades themselves;

Fig, 6 is a view taken on line 6-6 of Fig. 4;

Fig. 7.is a perspective side view of the sonic generator shown in Fig.6;

Fig. 8 is a section taken on line 8 8 of Fig. 5;

Fig. 9 is a cross-section through `a wedge-shaped propeller blade; and

Fig. 10 is a fragmentary showing of venturi tube type sonic generator ofwedge design, carried by a propeller blade.

Referring first to Figs. l through 3, the cleansing apparatus includesan upright tank 11 which has opposite front and rear walls 12, andopposite side walls 13 together forming an interior zone 14 forreceiving articles to be cleansed. Typically, such articles may comprisejet engine parts such as illustrated at 15 as retained in a rectangularbasket 16 received downwardly between the receptacle Walls into thecleansing zone 14. The basket is shown as seated on a grating 17typically having an egg-crate design and consisting of two sets ofintegral panels extending vertically and at right angles to one anotherto form spaces 18 therebetween into which soils removed from the parts15 are adapted to settle out of the path o f liquid circulation in thereceptacle.

The opposite walls 12 of th'e tank have recesses 19 formed therein whichopen transversely and divergently toward the cleansing zone 14. Each ofthe recesses is preferably in the form of a truncated pyramid havingfour divergent sides, a vertically spaced pair 20 of which divergerespectively toward the top and bottom of the receptacle. Similarly, ahorizontally spaced pair 21 of the recess sides diverge respectivelytoward the opposite sides 13 of the receptacle, and it will beunderstood that as a result of this recess configuration the liquid iscirculated in the tank in four loops which merge in the central regionsof the cleaning zone, as indicated by the arrows in Figs. l and 3.

Such liquid circulation is preferably effected by a hydrodynamicallydesigned and reversible thrust propeller 22, typically a three bladescrew propeller, operable to displace the bulk of the liquidtherethrough and alternately in axially opposite directions, asdistinguished from the action of a centrifugal impeller which throws thebulk of the liquid radially therefrom during impeller rotation andmoreover is not reversible to displace liquid in opposite directions asdesired. Each propeller is attached to a horizontally extending shaft 23projecting through the wall 12 at its flat square head or base 24 fromwhich diverge the upwardly and downwardly flared wall portions 20 andthe horizontally flared portions 21 of the receptacle wall 12. Attachedto the base 24 is the housing 28 of an electric motor, which ispreferably reversible so that the propeller 22 may be driven in oppositedirections. Each of these motors may be of the induction type, so thatby changing the polarity of the motor or the phase relationship of theapplied current a reversal in the direction of the drive transmitted tothe propeller may be secured. Current is applied to each motor throughswitching mechanism indicated at 30 which is operable to reverse thedirection of drive transmission to the propellers from the motors, forpurposes to be described. A master control switch is shown at 130.

In operation the liquid filling the tank is caused to be circulated bythe opposed propellers, which have a common horizontal axis of rotationas shown in Fig. l, such circulation being indicated by the arrows. Whenthe propellers are rotated so as to displace 4liquid axiallytherethrough, the liquid ows radially in a laminar or viscous flowpattern in each of the recesses 19 adjacent the flared wall portions 20and 21. Since those wall portions are outwardly to the top, bottom andopposite sides of the receptacle, the flow pattern therealong isstreamlined and not turbulent. Furthermore, each propeller is spaced ata distance from the head or base 24 substantially equal to the diameterof the propeller, it having been found that this dimensionalrelationship is most desirable from the standpoint of the viscous orlaminar ow pattern desired.

As the liquid leavesV the recess 19 in the four loops indicated by thearrows in Figs. l and 3, it circulates through the cleansing zone 14 inthe symmetrical ow pattern shown by the arrows, which assumes that opthetank or receptacle.

posite propellers are being rotated to displace liquid axiallytherethrough toward the heads or bases 24 and away from the cleansingzone. Such circulation is reversible by reversing the direction ofpropeller rotation to secure alternation of the impingement and sheareffects of the flowing high velocity liquid upon the soils coating theparts to be cleaned. Also, opposite propellers may be rotated so thatthe liquid circulates completely across the tank from propeller topropeller. Under these conditions, the liquid passes through bothpropellers in the same direction, whereas -in Fig. 1 the liquid passesthrough opposite propellers in opposite directions.

Shown in the upper regions of Fig. 1 and also in Figs. 2 and 3 is asplit cover or baie 32 extending in a horizontal plane and overlying thecleansing zone 14 within The cover halves are guided in tracks `33 so asto be slidable transversely outwardly away from the receptacle, leavingthe cleaning zone exposed for downward reception of the parts basket 16.Fig. 2 shows a plate-type heating element 35 secured to the inner sideof the receptacle flared wall portion 21 for heating the liquid thereinto desired temperature for maximum cleaning efficiency, typicalcleansing liquids consisting of trichloroethylene, cyclohexane, andsolutions of detergents, or acids or bases, such as strong causticsoltuions. Representative soils to be removed from parts such asbearings, shafts, compressor blades, sleeves and the like includegreases, oils, dust, tar, sludge, rust, resin, wax, carbon, lapping andbuflingcompounds, and steel particles.

The tank shown in Figs. l to 3 has a sloping bottom tapering downwardlyand away from the grating 17 to form a flow space 81 within whichcollected soils may flow laterally to the normally closed outlet 82.Liquid is typically supplied to the tank through an inlet 83 in wall 13below the level of the cover 32.

Each of the propellers 22 is better shown in Fig. 4 as having threeblades 40 together mounting a narrow ring 41 extending through slots 42in the blade tips and welded to the blades to be integral therewith.Welded to the inner and outer sides of the ring 41 mid-way between eachpair of blades are a radially spaced pair of sonic generators 47 each ofwhich, as shown in Fig. 6, is endwise elongated in plate form andincludes a rectangular body portion 48 and wedge shaped end portions 49integral with opposite ends of the intermediate portion 48.

As each generator plate 47 is rotated in either endwise direction aboutthe axis of the propeller shaft 23, its wedge apex edge 50 splits theliquid through which it passes as generally indicated by the arrows 51,the divided stream accelerating past the opposite tapering sides 52 ofthe wedge portion 49 and past the sharply defined rearward wedge edges53. Such liquid acceleration leads to a Bernoulli effect, productive ofsplit stream vibrations, cavitation bubbles and vortices shown at 54streaming rearwardly at opposite sides of the plate 47 rearward of edges53. Split stream vibration, and the formation and collapse of cavitationbubbles and vortices cause periodic pressure changes that propagate intothe liquid as waves of ultrasonic frequency.

The same elects are produced at opposite sides of the wedge-shapedrearward portion of the plate 47, as indicated in Fig. 6, withproduction of split stream vibration, and formation and collapse ofcavitation bubbles and vortices rearward of edges 53.

Referring back to Figs. 1 and 3, the ultrasonic energy generated by therotating wedge generators emanates from the ring-shaped paths ofgenerator rotation in the recessed zone 19 of propeller rotation, asindicated by the broken wave front lines 55 which travel laterally andsubstantially fill the mixing zone 14 of the receptacle with soundenergy. The angularity of the recessed walls 25, 26, and 27 enablesreflection of some incident ultrasonicwave energy back into the interiorof the cleaning zone. Sound energy propagating into zone 14 acts inconjunction with the high velocity flow of the -randomly oriented partssurfaces, making the ultrasonic surface treatment of the parts moreuniform, as brought out in the introduction. This effect is greatlyenhanced by the use of opposite propellers each of which mounts sonicgenerators, as shown in Fig. l. Since the fluid dynamic generatorscreate ultrasonic energy characterized by a broad frequency spectrum,there is negligible phase eect cancellation of energy waves travellingtoward the center of the cleaning Zone from opposite recesses 19.

A modified form of mounting of the sonic generators 47 is shown in Figs.5 and 8 wherein a single split diamond-shaped generator S7 is secured toopposite sides of the tip region of each propeller blade 40. In thisform of the invention, the generator halves 58 are generall;lsymmetrical and have sharply defined intermediate kedges S9` that areoutwardly presented to the relative flow of liquid thereover, asindicated by arrows 60, so as to produce the same effects of splitstream vibration, and cavitation bubble and vortex formation productiveof ultrasonics as described previously.

The manner in which the generator plates 47 and 57 are mounted to thepropellers as viewed in Figs. 4 and 5 is an important feature of theinvention; however, the invention broadly contemplates other methods ofmounting sonic generator wedgeplates to rotary means such as propellers,all for the purposes previously described. For example, many wedgeplates 57 can'be mounted on each propeller in radially spacedconfiguration. Also, the plates 47 can be mounted at their nodalvibration points 45 so as to vibrate and create ultrasonic energy, whenrotated. lt will also be noted that by virtue of the fact that the sonicgenerators 47 and 57 are tapered at their opposite ends, they willfunction to produce high intensity sonic energy during blade andpropeller direction in either rotary direction, enabling sonic cleaningtreatment of parts surfaces during the different tangential and normalforce treatment of the parts surfaces by the high velocity liquid, ascontemplated in the beginning portion of the specification. In all casesthe wedge plates are carried by the rotary means at a radially outwardlocation so that high intensity sonic energy will be produced in theliquid body.

Fig. 9 shows that the propeller blade itself may be wedge-shaped forcreating ultrasonic wave energy, a cross section through such a bladebeing indicated at 70. In Fig. l a venturi tube 7l is carried at the topright receptacle `forming anvinterior zone for receiving a body ofliquid and partsfto be cleaned thereinyrot'ary, means axially rotatablein the liquid received in thereceptacle and at one side of said zone,and means having blades for flowing liquid through said zone, and wedgev means carried' by said rotary means at a radially outward locationrelative thereto for high velocity rotary dis? placement in said liquidin the direction of wedge taper relatively to accelerate liquid over thewedge producing ultrasonic disturbances propagating in said liquid bodythrough said zone as the Wedge is rotated in said liquid.

3. Ultrasonic cleaning equipment, comprising an upright receptacleforming an interior zone for receiving a body of liquid and parts to becleaned therein, propeller means axially rotatable in the liquidreceived in the receptacle and at one side of said zone forcirculatingliquid therethrough, and wedge means carried by said propeller means ata radially outward location relative thereto for high velocity rotarydisplacement in said liquid in the direction of wedge taper relativelyto accelerate liquid over the wedge producing ultrasonic disturbancespropagating in said liquid body through said zone-as the Wedge isrotated in the liquid.

4. Ultrasonic cleaning equipment, comprising an upright receptacleforming an interior zone for receiving a body of liquid and parts to becleaned therein, said receptacle having a recess opening and divergentlytoward said zone, rotary means in said recess axially'rotatable in theliquid received in said receptacle for circulating liquid through saidzone,l wedge'means carried by said rotary means at a `radially outwardlocation relative thereto for high velocity forward rotary displacementin said liquid in the direction of wedge taper, said wedge means havinga forwardly tapering side terminating rearwardly at a sharply definededge, and means for rotating said rotary means at a speed such thatliquid relatively accelerates over the wedge tapering side and sharpedge producing ultrasonic disturbances propagating in said liquidthrough said zone.

5. The invention as defined in claim 4 in which said rotary meanscomprises a propeller operable to draw of a propeller blade 72, the tubebeing wedge-shaped in cross section, as shown, for creating ultrasonicwave energy as the tube is rotated by the propeller in a body of liquid.

'Other uses to which the rotary wedge generators described above may beput include the generation of ultrasonic wave energy in liquids otherthan cleaning liquid, as for example solutions to be emulsilied byultrasonic treatment.

I claim:

l. Ultrasonic cleaning equipment, comprising a receptacle forming aninterior Zone for receiving a body of liquid and parts to be cleanedtherein, rotary means axially rotatable in the liquid received in saidreceptacle for flowing the liquid therein, and wedge means carried bysaid rotary means at a radially outward location relative thereto forhigh velocity rotary displacement in said liquid in the direction ofwedge taper relatively to accelerate liquid over the wedge producingultrasonic disturbances propagating in said liquid body through saidzone as the wedge is rotated in said liquid.

2. Ultrasonic cleaning equipment, comprising an upliquid in a first highvelocity course of flow transversely from Within the interior of saidzone toward said recess and to return liquid in a second high velocitycourse of flow transversely away from said recess and toward theinterior of said zone.

6.V The invention as defined in claim 4 in which said wedge means hasforwardly tapering opposite sides terminating rearwardly at sharplydefined edges.

7. The invention as defined in claim 4 in which said last named means isoperable to rotate said rotary means alternately in forward and rearwardrotary directions, and in which said wedge means has forwardly andrearwardly tapering opposite sides terminating at sharply defined edgesrearward of said forwardly tapering sides and forward of said rearwardlytapering sides.

8. The invention as defined in claim 7 in which said-iY wedge meanscomprises a forwardly and rearwardly elongated plate having a pair of.said sharp edges at each side of the plate.

9. The invention as dened in claim 8 in which said wedge means isdiamond shaped and has a single sharp edge at each side thereof. l

l0. The invention as defined in claim 8 in which said wedge meanscomprises a plurality of wedge shaped plates spaced about the axis ofsaid rotary means.

l1. The invention as defined in claim 5 in which said wedge meanscomprises a plurality of wedge-shaped plates carried on said propellerblades.

12. The invention as defined in claim 5 including a ring mounting saidwedge means and carried by the propeller.

13. Ultrasonic cleaning equipment, comprising an upright receptacleforming an interior zone for receiving a' tacle having a recess openingand diverging toward said zone, rotary means in said recess axiallyrotatable in the liquid received in said receptacle for circulatingliquid through said zone, said rotary means including a propelleroperable to draw liquid in a rst high velocity course of ow transverselyfrom within thel interior of said zone toward said recess and to returnliquid in a second high velocity course of flow transversely away fromsaid recess and toward the interior of said zone, said rotary means alsoincluding a ring extending about the propeller axis of rotation andsecured to the outer portion of Ithe propeller blades, and wedge meansmounted by said ring for high velocity forward rotary displacement insaid liquid in the direction of wedge taper, said wedge means having aforwardly tapering side terminating rearwardly at a sharply dened edge,and means for rotating said rotary means at a speed such that liquidrelatively accelerates over the wedge tapering side and sharp edgeproducing ultrasonic disturbances propagating said liquid through saidzone.

14. Ultrasonic equipment, comprising means rotatable in a body ofliquid, and wedge means carried by said rotatable means at a radiallyoutward location relative thereto for high velocity rotary displacementin said liquid and for producing ultrasonic disturbances propagating insaid liquid body as the wedge is rotated therein, said wedge meanscomprising a propeller blade having a diamond shaped cross section.

15. Ultrasonic cleaning equipment, comprising rotary means axiallyrotatable in a body of liquid, said means having blades for owing saidliquid, and wedge means carried by said rotary means at a radiallyoutward location relative thereto for high velocity rotary displacementin said liquid in the direction of wedge taper relatively to accelerateliquid thereover producing ultrasonic disturbances propagating in saidliquid body as the Wedge is rotated therein, said wedge means comprisinga venturi tube having a wedge shaped cross section, said tube beingcarried by one of said blades.

l6. Ultrasonic cleaning equipment, comprising an upright receptacleforming an interior zone for receiving a body of liquid and parts to becleaned therein, said receptacle having recesses opening transverselyand divergently toward opposite sides of said zone, rotary means in eachrecess axially rotatable in the liquid received in said receptacle andoperable to draw liquid in a iirst high velocity course of owtransversely from within the interior of said zone toward said recessand to return liquid in a second high velocity course of flowtransversely away from said recess and toward the interior of said zone,and wedge means carried by said rotary means at a radially outwardlocation relative thereto for high velocity forward rotary displacementin said liquid in the direction of wedge taper, said wedge meansincluding opposite forwardly tapering sides at least one of which hasrearwardly and forwardly spaced sharply defined edges and means forrotating said rotary means at a speed such that liquid relativelyaccelerates over the wedge tapering side and rearward edge producingultrasonic disturbances propagating in said liquid body.

17. The invention as defined in claim 16, in which said rotary meanscomprises a screw propeller.

References Cited in the le of this patent UNITED STATES PATENTS 982,578Dilg Jan. 24, 1911 2,014,032 Sharpe Sept. 10, 1935 2,175,609 Leeb Oct.10, 1939 2,495,159 Chertoff Jan. 17, 1950 2,516,656 Smith July 25, 19502,607,568 Seavey Aug. 19, 1952

